1. Field of the Invention
This invention relates to improvements in an auxiliary nozzle for an air jet loom in which nozzle is arranged to provide assisting force to a weft yarn projected from a weft inserting nozzle and passing through an air guide channel formed in a warp shed, and more particularly to such an auxiliary nozzle configuration to stabilize the direction of the air jet ejected from the auxiliary nozzle regardless of any change of air pressure to be supplied to the auxiliary nozzle.
2. Description of the Prior Art
Air jet looms are usually provided with a plurality of auxiliary nozzles which are disposed along an air guide channel through which a weft yarn projected from a weft inserting nozzle passes to be picked into the shed of warp yarns. The auxiliary nozzles function to eject auxiliary air obliquely toward the air guide channel and to enhance the air stream passing through the air guide channel thereby providing a weft picking assistance force to the picked weft yarn. Such an auxiliary nozzle includes a nozzle body which is formed with a nozzle opening through which auxiliary air is ejected toward the air guide channel.
Concerning the shape of such a nozzle opening, a variety of shapes have been proposed, for example, as disclosed in Japanese Patent Publication No. 55-36735 and in Japanese Patent Provisional Publication No. 57-66152. The former publication shows an arrangement in which the nozzle opening consists of many small openings which are close to but separate from each other. The latter publication shows another arrangement in which the nozzle opening is a single one which extends in a linear position.
It is necessary to change air pressure supplied to the auxiliary nozzle in accordance with the kind of weft yarns. In the arrangement in the abovementioned former publication, the direction of the air jet from the auxiliary nozzle is relatively stable regardless of the change of air pressure which is supplied to the auxiliary nozzle. Since this arrangement is such that many small openings are directly formed in a side wall facing the downstream side in the weft picking direction, it is necessary to form each small opening one by one by means of drilling or electrospark machining and to regulate the diameter of each small opening at about 0.2 mm. In the case of by drilling, the diameter of a drill is as small as about 0.2 mm, and therefore it is necessry to carry out forming machining for each small opening one by one with the greatest care in order to prevent the drill from breaking and the center from coming off, thus requiring much time and effort. In case of electrospark machining, accidents may occur in which a discharge electrode unavoidably bends under heat during the opening forming operation since the diameter of the discharge electrode is smaller relative to the discharge voltage applied to the discharge electrode. Accordingly, the small opening is unavoidably curved in the axial direction of the discharge electrode. As a result, it is difficult to obtain small openings which are uniform in air ejection direction.
In the arrangement of the above-mentioned latter publication, when air pressure supplied to the auxiliary nozzle is changed with different kinds of weft yarn, the ejection direction of the auxiliary air ejected from the auxiliary nozzle is unavoidably scattered in the weft picking direction, particularly among respective auxiliary nozzles. Thus, auxiliary nozzles of the same kind cannot be effectively employed for applications where weft yarns of various kinds are picked.